Screen for centrifugal baskets.



E. ROBERTS.

SCREEN FOR CENTRIFUGAL BASKETS.

APPLlCATiON HLED AUG.18,I9I7.

UNTE STATES PATENT ()ICE.

- EUGENE ROBERTS, OF SALT LAKE CITY, UTAH, ASSIGN'OR TO SUGAR CENTRIFUGAL DISC HARGER CO., OF SALT LAKE CITY, UTAH, A CORPORATION OF UTAH.

SCREEN FOR CENTRIFUGAL BASKETS.

Specificationof Letters Patent.

. Patented Apr. 15, 1919.

Application filed August 18, 1917. Serial No. 187,011.

To all whom it may concern:

Be it known that L-EUGENE ROBERTS, citinew and useful Improvements in Screens for Centrifugal Baskets, of which the following is a, specification.

This invention relates to screens for centrifugal baskets such, for example, as are disclosed in Letters Patent of the United States to Roberts and Gibson dated July 18, 1914, N 0. 1,108,098, a further improvement of which is also disclosed in patent to Eugent Roberts, #1,160,325 dated November 16, 1915, and is intended to provide a screen so constructed as to reduce to a minimum the stretching or bulging of the interior portions of .the screen and also the breakage of the interlocking tongues due to the presence of the close perforations which are necessary for the escape of the liquid content to be separated.

Generally speaking, the invention consists of a metallic perforated sheet metal member,'the perforated area of which is sub divided into longitudinal strips by intervening portions or strips of relatively narrow width" to form a stiffening or protective selvage acting to preserve the annular or cylindrical shape of the screen when in use and also-so located with reference to' the interlocking tongues as. to form a protective selvage for the edges of said tongues to minimize their liability to breakage.

In the accompanying drawings are shown various views illustrating the preferred mode of embodying the principles of this invention in which,

Figure 1 is a plan or flat view of the entire screen before it is bent into annular form'for use in the centrifugal basket.

Figs. 2 and 3 are enlarged detail views showing the construction of the offset interlocking end edges of the screen and indicating the location of the narrow selvage portions with relation to the interlocking tongues.

Fig. 4 is an enlarged elevation showing the manner of joining or interlocking the two ends of the screen.

Fig. 5 is a detail cross sectional view on the plane 5-5 of Fig. 4.

Fig. 6 is a similar view on plane 6-6 of Fig. 4. g

It will be understood that in the centrifugal separation of sugar or other material the perforated wall of the centrifugal basket or receptacle is provided with a series of relatively large perforations for the escape of liquid and that it is customary to insert inside the basket a so-called screen or lining provided with closely arranged relatively fine perforations for the purpose of retaining the solid particles and allowing the liquid to escape. The patents above referred to relate to a construction involving the proper interlocking of the two ends of the screen to make a close joint over which the plow or scraper used for discharging the sugar may ride without inj ury. 7

It has been found that the operation of punching out the perforations in the sheet forming the screen or lining acts to cause a certain amount of stretch or bulge in the interior parts of the screen which stretch may also be increased by the great pressure of the solid matter due to centrifugal action when the machine is in operation. Furthermore the slitting of one edge portion through the perforated body of the sheet metal so removes the tongues formed thereby that they are more easily broken. Be-

- side, the raggedness of theedges tends to increase the difiiculty of inserting the tongues with their cooperating holding slots in the other end edge of the screen.

To remedy these difficulties is the purpose of this invention.

In the practice of this invention according to the form illustrated in the drawings, instead of perforating the entire body portion a of the screen or lining there is left a series of very narrow selvage strips a alternating with the much wider longitudinal perforated strips a throughout the body of the screen.

These imperforate portions or strips of the screen are located so as to include at about the middle line of their end portions the slits b which extend longitudinally inward from one end of the screen a to form the interlocking tongues b so that the edges of the tongues are left with a narrow 1m-. perforate selvage leaving a smooth edge which is not only more easily inserted into the receiving or cooperating slots 0 but also serve to materially strengthen the individual tongues and lessening their tendency to become broken under repeated manipulation and use.

The longitudinal selvage strips or portions a need not be over three-sixteenths of an inch in width to perform acceptably the functions for which they are intended. With the arrangement shown this would leave a selvage at the upper and lower edgeof each tongue I) about three thirty-seconds ofan inch in width which is suflicient to protect the tongue against undue breakage. With'these imperforated selvage strips ex tending both at thetop and bottom edges of the screen and also at reasonably frequent intervals through the interior portions of the screen it will be found that the bulging of the middle portion of the screen incident to the stretch caused by the punching or perforating die will be obviated and that the screen when assembled in the basket will have more nearly a true cylindrical form, not only when inserted but that the tendency to buckling thereafter will also be obviated.

It will be understood that in the form of the. screen illustrated in the drawings the transversely. extending slots located in one end portion of the screen are spaced apart substantially the width of one tongue and that alternate tongues are inserted through the slots 0 from the inside outward while the intermediate tongues are passed outside of the end selvage portion 0 as indicated in Figs. 5 and 6 respectively. In the form shownthose portions of the slotted end selvage located'between the respective slots and the end edge of the screen as indicated at c are struck up or slightly offset from the plane of the rest of the screen to facilitate the insertion of the tongues through the slots.

In the drawings'the stipplings to indicate the fine perforations is applied to the corner screen, the boundaries or limits of the perforated areas being indicated by the continuing dotted lines.

What I claim is:

1. A screen for a centrifugal basket comprising a perforated sheet of metal adapted to be bent into annular form, one end being provided near its edge with a series of transverse slots, the other end edge-being slitted and longitudinal SCIK en being formed of relatively wide perforated portions extending longitudinally of the screen and intervening relatively narrow imperforate portions acting as stiffening selvages for the perforated portions to prevent buckling, substantially as described.

3. A screen of a centrifugal basket comprising a metallic sheet adapted to be bent into annular form and having its end edges respectively provided with transverse slots,

tongues to form an interlocking jOlIlt, narrow portions of said sheet being left imperforate to form an external selvage, the interior body portion of said sheet beingsubdivided into relatively wide longitudinal perforated strips and intermediate imperforate relatively narrow strips, said imperforate strips being located to include the edges of the aforesaid tongues in order to strengthen said tongues and prevent bulging of the interior perforated portions of the screen, substantially as described.

4:. A screen for a centrifugal basket embracing in its construction a sheet of perforated material whose end edges are respectively slitted, longitudinally to form tongues and slotted transversely to form receiving slots for some of said tongues, the interior portions of said tongues being perforated while the narrow edge portions of said tongues are left imperforate to form a smooth selvage edge, substantially as de scribed.

In witness whereof, I have subscribed the above specification.

EUGENE ROBERTS. 

